disabled ItemSimilarity test until we can work out how to run them without MAHOUT_HOME and SPARK_HOME being set
MAHOUT-1541, MAHOUT-1568, MAHOUT-1569 fixed a build test problem, drivers have an option new to not search for MAHOUT_HOME and SPARK_HOME
Merge branch 'master' of https://git-wip-us.apache.org/repos/asf/mahout